The cell structure of a conventional color liquid crystal display device is basically composed of a substrate having a color filter and an opposite substrate having a conductive film formed on a transparent substrate such as a TFT array substrate. The color filter is usually produced, for example as disclosed in JP-B02-1311, by forming at first a black matrix on a transparent substrate, then forming pixels of red (R), green (G) and blue (B), and further forming on them transparent electrodes necessary for driving the liquid crystal in an electric field. As required, a transparent protective layer is formed between the pixels and the transparent electrodes.
The black matrix refers to the light screening regions disposed between the respective pixels, to improve the contrast of display in the display device, and to prevent the mal-function caused by the light incident on any active element such as TFT. Usually, the black matrix is formed by patterning a metal such as chromium or nickel or any of the oxides thereof, etc. laminated on a transparent substrate, or a mixture consisting of a light screening agent and a resin.
For assembling the cells, an alignment layer is formed on the transparent electrodes and is rubbed for aligning the liquid crystal, and the intermediate product is sent to the cell-assembling step, and is joined with an opposite substrate. Then, the liquid crystal is filled.
Furthermore, in recent years, liquid crystal display devices have become larger, or are being increasingly used as monitors. In this situation, they are demanded to be wider in viewing angle. Though the conventional TN system uses positive liquid crystal, VA (vertically alignment) liquid crystal display devices using negative liquid crystal are being developed, and furthermore, MVA (multi-domain vertical alignment) liquid crystal display devices have been developed as an improved version of VA (for example, Society for Information Display International Symposium Digest of Technical Papers, Volume XXIX, p. 1077˜1080). The MVA liquid crystal display devices are characterized by a wide viewing angle, and to divide the alignment on the pixels of the color filter, protrusions are provided on the surfaces of the TFT substrate and the color filter substrate, for controlling the liquid crystal aligning directions. In this system, the design of the protrusion for controlling liquid crystal alignment is technically important.